Educational appliance



A g- 1932- H. w. GEROMANOS I 4,

EDUCATIONAL APPLIANCE Filed Feb. 14. 1929 livenlon Patented Aug. 30, 1932 UNITED STATES HERCULES wAnLacnenaomalvos, vor nos'ron, massacnusmrs EDUCATYIOJNAL Ar'rLIA cE a lication filed February 14, 1929. Serial up. 339,931.

This invention relates to that classof edu-;

cational appliances designed more especially for use in the teaching of astronomy, a

It is well known that there isa slow westward movement or precession of the equi-v and college student finds considerable" dif ficulty in visualizing these movements and in understanding the effects ofthem. The present invention deals especlally with this problem and it aims to devise an apparatusv with which the precession of the equinoxesf can be clearly demonstrated. v The nature of the invention will be readily understood from the following description when read in connection with the accompan ing drawing, and thenovel features will particularly pointed out in the appended claims.

In the drawing, V g 1 Figure 1 is a side view of a precession demonstrator embodying this invention; and Fig. 2 is a vertical sectional view ofthe terrestrial globe which'forms a part of the apparatus-shown in Fig. 1. 1 The apparatus showniin the drawing includes a terrestrial globe which comprises a northern hemispherical section 2 and a southern hemispherical section-3, the lower part of the latter section, however, being cutaway. These sections are carried by a wheel 4 preferably made of metal and therefore having considerable mass. the globe structure and both the upper and lower margins of the wheel are grooved to receive the edges of the hemispherical sections 2 and 3, these sections being, somewhat reduced at the equatorial region in order to accommodate the wheel. I j 2 is clamped to the wheel by'a tube 5 having a flattened head 6 which bears onthe' section 2 at the polar region, while its lower end is threaded on a boss 7 that projects upwardly from the central portion of the wheel. The southern hemispherical section 3 is held in place by a ring 8 on which the lowered'ge The wheel forms part of,

The upper section of said section bears, and this ring is: secured" in place by posts 9 which extend downwardly ,from and are fastened to the wheel 4.

In order to support the globe for rota motion a pivot stud 10 is threaded throug the central part of the wheel 4, and it is' provided with a hardened oint at its lower end. This point normal y rests in a hardened socket formed in the upper end of an 7 upright post'll which is mounted in a base so 12. It willbe observed that this arrange-v me'nt not only permits the globe to revolve about its own axis, butalso permits said axes to swing through a considerable arc.

The threaded mountjing of thepivotstud 66 10 in the wheel 4 permits the axial adjustment of the; stud relatively to the wheel, andthefstud'may be locked in its adjusted posit1on by a set screw 13. Theupper end of this stud is secured fast in the lower end 1 of a tube or hollow post 14 which fits closely in'the tube 5 and projects for a considerable distance beyond the north polar region of the globe so that it-serves to representthe north pole. This post 14 is capped by a grooved or knurledknob 15 having a pointed extremity 16- lying in the axis ofrotation. of the globe.

Encircling the globe is an annular plate 17 I which is supported on a oke 18slidably somounted on the post ll and the yoke is normally locked in a stationary position by'a set screw 19. This a'nnularpla'te represents the plane of the ecliptic: The :position of the north pole of the ecliptic is indicated by apointer 20 which is supported immediately above the globe and is supportedon the end of a curved rod 21 mounted rigidly in the plate 17. V k In order to produce the desired precessional motion provision is made for adjusting the. relationship betweenthe center of gravityof the "globe and the parts rotating therewith andthe point of the pivot 10. While this can be done by adjusting the pivot 10, it is preferable to provide some additional, more easily operable means for accomplishing this result. For this'purpose the wheel 4 has a large boss 22 formed'on its lower side and externally screw threaded. A large inter- 29: point 16 will-revolve around the pointer 20.

nally threaded nut 23 is mounted on this boss so that it can be adjusted axially of the wheel to raise or lower the center of gravity of the entire rotating mass.

In using the apparatus the pivot 10 is usually so adjusted that its point lies substantially inthe center of gravity of the globe, it being borne in mind that the wheel forms a part of the globe. The weight of the parts are so proportioned that when the nut 23 is at theupper limitofits range of adjustment the center of gravity of the globe and the parts revolving therewith'is slightly below the point of the pivot 10. It ,now the globe is revolved by twirling the knob 15, the

axisoftheglobes being inclined atapproximatelythe proper angle, the globe will have, in addtion to itsrotary motion about its own axis, a slow gyratory motion in which the At thesame time the-imaginarypoints of intersection of the plane of the wheelt with the plane of the annular plate 17 will slowly travel around the plate, thus illustrating the precession of the equinoxes. The rate of this precessional motion can be increased by low-' eringthe weight 23. The ring 1 17 prefer ably is divided by "shallowradi-al grooves into twelve segments corresponding 1 to the twelve months of the year. This markingor division of; the 'rin'g thus affords points of reference for the study of theprecessional motion and also illustrates the effect" offlthis motion in bringing the. equinoxes into di fi'erent months of the year.

Theapparatus thus demonstrates to the student the precession of the equinoxes and the slowrotat-ion of the earths axis around the poles of :the ecliptic.

This apparatus also may conveniently be used=to illustratenutation; That is, the.

slight irregularity in motion or wabbling which the earth has and which naturally is mostreadily observed at-thepoles. In the present apparatus this motion can be illustrated: bygiving the globe a slight wabbling movementwhen :it is spun or set into rota-V a preferred embodiment of my invention, it I Having thus described my invention, What I desire to claim as new is:

1. In an apparatus of the character described, the combination of a terrestrial globe, means supporting said globe for rotation on its axis and also for gyratory motion of said globe and axis, and means adjustable to change the relationship between the center of, gravity of said globe and the parts revol ving therewith andthe point about which the-globe gyrates.

2. In an apparatus of the character described, the combination of a terrestrial globe, means supporting said globe for rotation on its axis and also for gyratory motion of said globe and axis, and parts associated with said globefor'indicating the plane and one pole of the ecliptic;

3. In an apparatus of the character described; the combination of a terrestrial globe, means supporting said globe for rotation'on'its axis and also for gyratory motion of saidglobe and axis, an annular plate encircling saidglobe, means for supporting said plate. in position to represent the plane of the ecliptic, and a pointer. mounted above the globe-and indicating the position of one pole of the ecliptic.

-4. In an'apparatus of the character described, the combination of a terrestrial globe having considerable mass, means supporting said globe for rotation, said means including apivot point'and a socket therefor both located in the globe and permitting the globe to revolveon its axis and also permitting said axis to gyrate, and means adjustable to raise orlower, the center of gravity of the globe and the parts revolving therewith relatively to said pivotal support.

5. In an apparatus of the character described, the combination of a terrestrial globe including 'a wheel of considerable mass located in the equatorial region, a pivot carried by saidwheel, a post projecting into the lower end of said globe, and a socket for said pivot located in the upper end of said post.

6; In an apparatus of the character described, the combination of a terrestrial globe including a wheel'ofconsiderable mass locatedin the equatorial region, a pivot carried bysaid wheel, a post projecting into the lower'end of said globe, a socket for said pivot located in the upper end of said post, and means adjustable to vary the relationship between said pivot andthe center of gravity of said globe and the parts revolving therewith.

7. In an apparatus of the character described, the combination of a terrestrial globe including a wheel of considerable mass located in the equatorial region. a pivot carried by said wheel, a postprojecting into the lower end of said globe, a' socket for said pivot located in the upper end' of said post, and a post projecting from the north polar region of the globe and having a knob at its upper end.

8. In an apparatus of the character described, the combination of a terrestrial globe including a wheel of considerable mass located in the equatorial region, a pivot carried by said wheel, a post projecting into the lower end of said globe, and a socket for said pivot located in the upper end of said post, said p vot bein adjustable in said wheel 1ongitudinally of said axis.

9. In an apparatus of the character descr bed, the combination of a terrestrial globe including a wheel of considerable mass located in the equatorial region, a pivot carried by said wheel, a post projecting into the lower end of said globe, a socket for said pivot located in the upper end of said post, and a weight carried by said wheel and adjustable axially of the wheel.

10. In an apparatus of the character decluding a pivot point and a socket therefor both located inside the globe.

HERCULES WALLACE GEROMANOS.

scribed, the combinationof a terrestrial globe including a wheel of considerable mass located in the equatorial region, a pivot carried by said wheel, a post projecting into the lower end of said globe, a socket for said pivot located in the upper end of said post, said wheel having an externally threaded central boss thereon, and a weight threaded on said boss and adjustable axially with reference to the wheel.

11. In an apparatus of the character described, the combination of a terrestrial globe including a wheel of considerable mass located in the equatorial region, a pivot carried by said wheel, a post projecting into the lower end of said globe, a socket for said pivot located in the upper end of'said post, a circular member encircling said globe and serving to indicate the plane of the ecliptic, a pointer located above the globe and indicating the position of one pole of the ecliptic, and a post projecting from thenorth polar region of said globe and having a point to cooperate with said pointer.

12. In an apparatus of the character described, the combination of a terrestrial globe including a wheel of considerable mass located in the equatorial region, a pivot carried by said wheel, a post projecting into the lower end of said globe, a socket for said pivot located in the upper end of said post, a stationary annular member encircling said globe and serving to indicate the plane of the ecliptic, a stationary pointer mounted above said globe and indicating the position of one of the poles of the ecliptic, and a post projecting from the north polar region of said globe.

13. In an apparatus of the character described, the combination of a terrestrial globe, and means supporting said globe both for rotation about itsaxis and also for the gyratory movement of said axis, said means including parts extending into said globe and supporting it internally. 

